A team of researchers from Brazil and other countries has carried out work that points to natural regeneration as an efficient and low-cost measure for forest restoration. The study, with the participation of researchers from the Federal University of São Carlos (UFSCar), the University of São Paulo (USP) and the University of Connecticut, United States, was published in the Journal of Applied Ecology.
The focus of the research was the watershed of the Piracicaba River, whose extension is more than 12 thousand km², located between the southeast of the State of São Paulo and the extreme south of Minas Gerais. It provides potable water to about 10 million people, including much of São Paulo, and is in the second most threatened region of the Atlantic Forest biome, with only 7 percent of the remaining forest cover.
Forest restoration in the basin can help with water conservation; however, the high costs of restoration are one of the major challenges to overcome. The costs, besides being high, are variable for two reasons: the natural characteristics of each site, which influence the success of the beginning of the forest restoration process; and economic losses from conversion of agricultural land to forest reserve areas, which depend on the economic return of planted crops and land prices (so-called opportunity costs).
“These costs can be significantly reduced when it is possible to use natural regeneration itself, a natural process of reestablishing the forest after large-scale disturbances,” says Paulo Guilherme Molin, a professor at the Campus Lagoa do Sino at UFSCar and one of the authors of the work, along with Robin Chazdon of the University of Connecticut; and Silvio Frosini de Barros Ferraz and Pedro H. S. Brancalion, both from USP.
As natural regeneration requires conditions that are not universally present, the team of researchers used satellite imagery to identify sites where forests grew naturally between the years 2000 and 2010 across the watershed and used this information along with environmental and to predict the occurrence of natural regeneration in the next 10 years (2010 to 2020). They also calculated the costs of implementing restoration measures, based on predicted probabilities, as well as opportunity costs of land, which vary according to current and previous land use, landscape characteristics and market contexts.
Three alternative strategies were applied during the study to restore the native forest cover of 15,000 hectares in three landscape units of 40,000 hectares that represent a gradient of land use intensity and forest cover (landscape of mechanized agriculture, dominated by cane plantations, pasture landscape, and forest landscape, dominated by pastures, but with greater forest cover – 31%). An initial strategy prioritized the restoration along the streams, similar to the one applied by the “New Forest Code”. A second performed the restoration at spatially random locations; and a third prioritized low cost restoration in areas with high probability of natural regeneration.
The research indicated that, throughout the basin, both for agricultural and pasture areas, natural regeneration was favored in regions with declivity above 10%, distances less than 200 meters of bodies of water and 100 meters of forest remnants. In the forest landscape, 44.5% of the lands had high potential for natural regeneration, compared to only 7.3% in the landscape unit with mechanized agriculture.
“The restoration strategy, based on natural regeneration and the prioritization of land uses with lower opportunity costs, resulted in enormous savings in implementation costs and total costs in the three landscape units. When total costs were included, the magnitude of the economy was higher in the unit of mechanized agriculture, with a 20.9% lower cost (something around US $ 20.5 million economy), compared to the prioritization based on riparian zones [regions directly related to the d ‘ water], “explains Molin.
The study also showed that the prioritization of areas with high potential for natural regeneration has increased the cost-benefit ratio in relation to sequestration and carbon stock and landscape connectivity. The cost reduction strategy minimized the total cost of above-ground carbon stock in the three landscape units, averaging $ 74 per additional ton of carbon stored in restored forests in mechanized agriculture landscapes; US $ 58 in pasture landscapes; and $ 41 in forest landscape units. This analysis is one of the first to actually calculate the cost of carbon stock through forest restoration, demonstrating that these costs are much higher than the current carbon price in the voluntary market.
“Our approach has the potential to contribute to public policies, such as the current implementation of the ‘New Forest Code’, specifically with the Environmental Regularization Program that regulates where and how owners should restore and reforest their irregular or degraded areas,” concludes Molin . The work was funded by the Coordination for the Improvement of Higher Education Personnel (CAPES), the Sciences without Frontiers program and the Foundation for Research Support of the State of São Paulo (FAPESP). The full article can be accessed at https://bit.ly/2LSxL2n.
This text was translated by machine from Brazilian Portuguese.